Sewing machines with needle and loop taker operable not in predictably timed relationship



NOV. 4, 1969 JOHNSON 3,476,067

. SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLE NOT IN PREDICTABLYTIMED RELATIONSHIP Original Filed Feb. 5, 1966 5 Sheets-Sheet 1INVENTOR.

Ralph E. Johnson BY wylrronwr NOV- 4. 1969 R. E. JOHNSON SEWING MACHINESWITH NEEDLE AND LOOP TAKER QPERABLE NOT IN PBEDICTABLY TIMEDRELATIONSHIP riginal Filed Feb. :3, 1966 5 Sheets-Sheet 2 INVENTOR.Ralph E. Jalmsan I BY W 2;T0AWY 3,476,067 ITH NEEDLE AND LOOP TAKEROPERA BLE Nov. 4, 1969 R. E. JOHNSON SEWING MACHINES W NOT INPREDICTABLY TIMED RELATIONSHIP inal Filed Feb. 5. 1966 Orig 5Sheets-Sheet Fig. 5.

mvsmox. Ralph E. Johnson Nov. 4, 1969 R. E. JOHNSON 3,475,067

SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLE NOT IN PREDICTABLYTIMED RELATIONSHIP Original Filed Feb. 5, 1966 5 Sheets-Sheet;

Ralph E. Johnson BY W gamma-r I34 37 I52 '55 I I50 I36 E 4k I04 B2133 5I20 I21 I22 Fig 7 INVENTOR. I

Nov. 4. 1969 R. E. JOHNSON 3,476,067

SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLE NOT IN PREDICTABLYTIMED RELATIONSHIP Original Filed Feb. 5, 1966 5 Sheets-Sheet Fig.ll.

BAR CRANK ANGLE 6 80" DEAD l N VENTOR. Ralph E. Johnson BY anna/MrUnited States Patent SEWING MACHINES WITH NEEDLE AND LOOP TAKER OPERABLENOT IN PREDICTABLY TIMED RELATIONSHIP Ralph E. Johnson, Boonton, N.J.,assignor to The Singer Company, New York, N.Y., a corporation of NewJersey Original application Feb. 3, 1966, Ser. No. 524,949, now PatentNo. 3,420,200, dated Jan. 7, 1969. Divided and this application Dec. 15,1967, Ser. No. 690,868

Int. Cl. Db 57/14, 69/02, 49/00 US. Cl. 112-182 4 Claims ABSTRACT OF THEDISCLOSURE A lockstitch sewing machine is disclosed having areciprocating needle and a rotating loop taker with a drive providingfor a nominal speed ratio of three revolutions of the loop taker duringeach needle reciprocation. The drive for the loop taker is, however, asmooth belt incapable of maintaining a precise timed relationshipbetween the needle and loop taker. A needle thread take up mechanism isdisclosed which provides in a novel and advantageous manner for the widevariations in thread demand which are occasioned by the untimedoperation of the loop taker and needle of this sewing machine.

CROSS REFERENCES TO RELATED APPLICATIONS This application is a divisionof my co-pending U.S. patent application Ser. No. 524,949, filed Feb. 3,1966 and now U.S. Patent No. 3,420,200, dated Jan. 7, 1969.

FIELD OF THE INVENTION This invention relates to lockstitch sewingmachines and particularly sewing machines in which the loop taker andthe needle are operable in untimed relationship.

It is an object of this invention to provide a sewing machineconstruction in which a drive for the needle and loop taker provides fora nominal speed ratio therebetween but without provision for maintenanceof a predicatable relationship in time as between the motion of theneedle and loop taker and to provide an organization of sewing machineparts and devices ancillary to the needle and loop taker which canadvantageously accommodate the variations in sewing conditions occurringbecause of the absence of predictable timed relation be- 1 tween theneedle and loop taker.

DESCRIPTION OF THE PRIOR ART Without exception, conventional sewingmachines have heretofore provided actuating mechanism for operating theneedle and the loop taker in precisely timed relationship. Although awide variety of inventions have heretofore been used for needle and looptaker actuation including non-uniform velocities, dwells etc., themotions of needle and loop taker have always been preciselyinterrelated. In my prior US patent application Ser. No. 439,420, filedMar. 12, 1965 and now U.S. Patent No. 3,386,401 dated June 4, 1968 isdisclosed a sewing machine in which a needle and loop taker are capableof sewing lockstitches while being actuated by completely separate andunrelated sources of motive power, i.e., with complete absence of anytimed relation therebetween.

3,476,067 Patented Nov. 4, 1969 "ice SUMMARY OF THE INVENTIONDESCRIPTION OF THE DRAWINGS With the above and additional objects andadvantages in view as will hereinafter appear, this invention comprisesthe devices, combination and arrangements of parts hereinafter describedand illustrated in the accompanying drawings of a preferred embodimentin which:

FIG. 1 represents a perspective view of the sewing machine frametogether with the stitch forming instrumentalities, actuating mechanism,and control means therefor in modular form in accordance with thisinvention with each module shown detached from the sewing machine frame,

FIG. 2 represents a head end elevational view of an assembled sewingmachine of the type illustrated in FIG. 1 and including a supportingbase and an electric drive motor,

FIG. 3 represents a handwheel end elevational view of the assembledsewing machine of FIG. 2, with a portion of the handwheel broken awayexposing the stitch length adjusting means,

FIG. 4 represents a front elevational view of the assembled sewingmachine of FIG. 2 with portions of the actuating mechanism illustratedin vertical cross section,

FIG. 5 is an enlarged cross sectional view taken substantially alongline 5-5 of FIG. 2 illustrating the work feeding mechanism,

FIG. 6 represents a top plan view of the loop taker module of thisinvention as secured in place on the sewing machine frame,

FIG. 7 is a cross sectional view taken substantially along line 7-7 ofFIG. 6 illustrating the loop taker,

FIG. 8 is a top plan view of the loop taker of this invention,

FIG. 9 is a top plan view of the bobbin case,

FIG. 10 represents a head end elevational view of an assembled sewingmachine of the type illustrated in FIG. 1 and including a portion of anend cover plate applied thereto together with a representation of thepath of motion of the needle thread take up eyelet, and

FIG. 11 is a graph indicating the thread demand of the stitch forminginstrumentalities as compared with the thread control attained by thetake up.

Referring particularly to FIG. 1, the machine frame is indicatedgenerally at 11; the sewing needle module at 12; the loop taker moduleat 13; and the actuating and control module at 14.

The frame 11 comprises a C shaped member which may be of uniform crosssection and includes a pair of sub: tantially parallel free extremities15 and 16 joined by a Cl nnecting portion 17. The frame may befabricated in tl is shape by a bending or forging operation or it may becast in this shape. Only two accurately machined surfaces are requiredon the frame 11 and in the preferred embodiment illustrated in thedrawings these surfaces are a cylindrical portion 18 turned on the freeextremity of the arm 15 to accept the sewing needle module 12, and aslabbed portion 19 milled on the free extremity of the arm 16 upon whichthe loop taker module 13 is located. The axis of the cylindrical portion18 is preferably parallel to the plane defined by the slabbed portion 19and the distance therebetween is preferably formed to an accuratepredetermined dimension. The frame 11 may also be formed with provisionfor fastenings, such as tapped holes 20 and 21 illustrated in FIG. 1, toaccommodate fastening screws 22 and 23 for the actuating and controlmodule 14, the tapped holes 24 and 25 to accommodate fastening screws 26and 27 for the loop taker module 13, and the tapped hole 28 toaccommodate the fastening screw 29 for a supporting block 30 illustratedin FIG. 4. It will be appreciated, however, that other known types offasteners such as clamps might be used in place of these threadedfasteners which would not require any machining of the frame 11 for thefasteners and the tapped holes 20, 21, 24, 25 and 28 need not be locatedwith a high degree of accuracy.

The needle module 12 comprises a support plate 40 to the inside surfaceof which is secured a block 41 formed with a bore 42 which may beaccommodated on the cylindrical machined surface 18 of the frame arm 15.The block 41 is drilled and tapped, as at 43, for a set screw 44 bywhich the needle module 12 may be secured relatively to cylindricalmachined surface 18 is selected axial and angular positions thereon.

To the outside surface of the support plate 40 is secured a bracket 45between the outturned arms 46 and 47 for endwise reciprocatory motion isa needle bar 49 carrying at its lower extremity a needle clamp 50 inwhich an eye pointed thread carrying sewing machine needle 51 issecured. The upper extremity of the needle bar is transversely aperturedto accommodate a pivot screw 52 which carries a roller 53 which rides ina guide slot 54 in the support plate to prevent turning of the needlebar.

The support plate 40 above the guide slot 54 is formed with concavebearing seat 55 having the shape of a spherical section. Accommodated inthe bearing seat 55 is the spherically shaped collar portion 56 of astud shaft 57 formed with an axial bore 58. The stud shaft 15 formedintegrally with a crank arm 59 at one side of the collar portion 56 andadjacent to the other side of the collar portion, the stud shaft isexternally shouldered and accommodates a bifurcated leaf spring 60secured by a fastening screw 61 to the support plate 40, yieldinglyconstraining the collar portion against the bearing seat.

Pivotally connected to the crank arm 59 by a pivot pin 62 is the upperextremity of a needle bar drive link 63 which is formed at the lowerextremity with an inturned clevis 64 straddling the upper extremity ofthe needle bar 49 and pivotally connected thereto by the pivot screw 52.The needle bar drive link 63 is formed opposite the clevis 64 with arearwardly extending take up arm 65 terminating in a threadaccommodating eyelet 66 which, as will be described hereinbelow,controls and meters the thread which is directed to the eye of theneedle.

Also endwise slidable in the outturned arms 46 and 47 is a presser bar70 having a conventional presser foot 71 secured to its lower extremity.A lateral stud 72 secured to the presser bar extends through a guideslot 73 in the support plate 40 to prevent the presser bar from turning.The lateral stud 72 is engaged by one arm of a coil spring 74 of whichthe other arm abuts beneath the block 41 so as to bias the presser footdownwardly. A presser lifting cam member 75 pivoted on the support plate40 may also be disposed beneath the lateral stud 72 by which the presserfoot may be elevated.

The outturned arms 46 and 47 of the bracket 45 may support a sheet metalguard plate 80 to which is secured a conventional thread tensioningdevice 81 which includes thread tensioning friction disks 82, aconventional check spring 83 and a thread guiding post 84. Thread from asource of supply (not shown) is directed to the friction disks 82 of thethread tension device 81 looped about the check spring 83 and thence tothe take up eyelet 66. From the take up eyelet the thread is directedthrough a thread guiding eyelet 85 formed in a pin 86 adjacent to thethread tensioning device 81, next to a thread guide 87 secured to theguard plate 80, and then to the needle eye.

The loop taker module 13 is assembled on a plate 100, which is drilledto accommodate fastening screws 101 and 102 threaded into tapped holes24 and 25, respectively, in the frame 11 by which the plate is securedon the surface 19. Preferably, the screw 101 is formed with a shoulderedhead 103 serving to locate the loop taker in sewing position as will bedescribed hereinbelow. Assembled-on the plate 100 and sustained incooperating relation as a unitary module therewith are the loop taker,indicated generally as 104, the work feeding instrumentalities,indicated generally as 105.

The loop takes is carried by a swinging frame hinged to the plate 100.The swinging frame comprises an upper arm 106 which extends above theplate 100, and a lower arm 107 rigidly secured to the upper arm by aspacer 108. A second spacer 109 secured to the lower arm 107 is drilledand tapped for a headed hinge screw 110 which is extended through boththe plate 100 and the upper arm 106 and bears against the upper arm byway of a spring washer 111. Encircling the second spacer 109 is a twoarmed Wire spring 112 of which one arm bears against the frame arm 16and the other bears against the spacer 108 to bias the swinging frametoward the plate 100. An abutment 113 formed on the upper arm 106 of theswinging frame engages the shouldered head 103 of the fastening screw101 to locate the swinging frame in a predetermined operative positionrelatively to the path of reciprocation of the needle 51.

The loop taker 104 as illustrated in the drawings, is carried by theswinging frame and is so disposed thereon as to occupy a positioncooperative with the needle 51 in the formation of stitches when theswinging frame abutment 113 is seated against the shouldered head 103 ofthe factening screw 101. The loop taker may be of any known orconventional type suitable for the formation of either chain orlockstitches as may be desired. Indeed, the novel organization of thesewing machine of this invention provides for the ready exchange of looptaker modules 13 to substitute one type of loop taker for another. Theloop taker illustrated on the accompanying drawings is a lockstitchforming loop taker which operates in accordance with the principles setforth in my above mentioned copending US. Patent No. 3,386,401, to whichreference may be had, which does not require that the loop taker bedriven in any predetermined timed relationship with the needlereciprocation. Moreover, the specific features of construction of theloop taker illustrated in the accompanying drawings also forms thesubject of my co-pending US. patent application Ser. No. 537,065, filedMar. 24, 1966 and now U.S. Patent No. 3,382,826, dated May 14, 1968, towhich reference may be had, only that brief description of the looptaker will be set forth hereinbelow as will provide an understanding ofthe operation of the sewing machine of this invention.

Referring particularly to FIGS. 7 and 8, the loop taker 104 takes theform of a rotary hook and includes an inverted conical basket secured bypins 121 to the upstanding collar portion 122 of a belt pulley 123. Thepulley 123 is freely journaled on a bushing 124 surrounding a stationarycylindrical post 125 which is secured, as by a screw 126, to the lowerarm 107 of the swinging frame. Secured, as by a force fit into a shallowcounterbore 127 in the rim of the basket 120, is a flat annular ring 128formed with a plurality of internally extending thread seizing beaks129. A pin 130 set into the basket in a notch 131 in the ring 128 servesto lock the ring for rotation with the basket.

A bobbin case supporting tray 132 is fixed to the top of the stationarypost 125 within the rotary hook basket 120. The stationary tray isformed with a flat bottom 133 and with two angularly arranged upstandingsidewalls 134 and 135 which support and locate a bobbin case, indicatedgenerally at 136. The bobbin case 136 is formed with angularly arrangedside surfaces 137 and 138 which abut the tray sidewalls and with aflange 139 which overlies the flat angular ring 128 of the rotary hook.The underside of the bobbin case rests upon the fiat bottom 133 of thetray except where the bobbin case is formed with a shallow recess 140shaped generally circular but with a chord 141 extending across the oneside.

The upper arm 106 of the swinging frame is formed with an opening 150above the rotary hook which exposes a cavity 151 in the bobbin caseadapted rotatably to accommodate a thread carrying bobbin 152. A springfinger 153 secured by a pivot screw 154 to the upper arm 106 of theswinging frame overlies and bears downwardly against the bobbin 152 andthus also biases the bobbin thread case upon the stationary tray 132. Aleaf spring 155 carried on the upper arm 106 also engages the bobbincase side surface 138 serving to constrain the bobbin case yieldingly inposition within the rotary hook.

The loop taker module may also carry the work feedfeedinginstrumentalities of the sewing machine particularly wherein a drop feedis desired such as that illustrated particularly in FIGS. 5, 6 and 7. Itis pointed out, however, that using the module concept of constructionas taught by this invention, other forms of work feed mechanism might beused, as for instance, a top feed mechanism carried by the needle module12 might be employed.

Referring to FIGS. 5, 6 and 7, the drop feed mechanism 105 includes afeed dog 160 arranged beneath the presser foot 71. The forward extremityof the feed dog rests upon the plate 100 and in the rearward extremityis formed with a notch 161 embracing the upper portion of a rock arm 162which is fast on a rock shaft 163. The rock shaft 163 is journaled inspaced bearing lugs 164 downturned from a bar 165 which is supportedbeneath the plate 100 by two spacers 166. A throat plate 167 formed withslots 168 accommodating the feed dog and with a needle aperture 168' issecured to a vertical stud 169- which is slidable vertically in a hole170 in the plate 100 and a hole 171 in the bar 165. Pivoted to the stud169 on a pin 172 is a lever 173 to which is pivoted, as at 174 a fulcrumroller 175 which snugly fits between the underside of the plate 100 andthe bar 165. Movement of the lever 173 causes the throat plate to riseand fall alternately to cover and to expose the feed dog through thethroat plate slots. Oscillation of the rock shafts 163 serves toreciprocate the feed dog along the throat plate slots. Operation of thefeed mechanism, therefore, requires simply that rocking movement beimparted to the lever 173 and that related oscillatory movement beimparted to the rock shaft 163.

The means for importting such related operative movement to the feedmechanism as well as for imparting turning movement to the loop takerand to the needle bar driving crank are provided in the actuating module14 which will now be described.

The actuating module 14 is assembled on a supporting plate 180 which isaffixed to the connecting limb 17 of the frame 11 by the aforementionedfastening screws 22 and 23. As illustrated in FIG. 4, the supportingplate 180 is formed near the top with a concave bearing seat 181 havingthe shape of a spherical section.

A bushing 182 having a spherically shaped peripheral portion 183accommodated in the bearing seat 181 is formed with an external shoulder184 upon which a bifurcated spring 185 engages to hold the bushingresiliently in the bearing seat 181. The spring 185 is secured to theplate 180 by a headed adjusting pin 186 which passes through the plate180. A finger grip 187 projects from the headed pin 186 so that themachine operator may at will change the angular position of the pin 186,and at the opposite side of the plate the pin 186 has secured to it acollar 188 formed with a diametrical slot 189 for regulating the feedstroke of the work feeding mechanism.

Journaled in the bushing 182 is a shaft 200 adapted at the freeextremity to be accommodated in the axial bore 58 of the stud shaft 57on the needle module 12. A flat 201 formed on the shaft 200 may be usedin cooperation with a set screw 212 threaded into the stud shaft 57 tosecure the stud shaft onto the shaft 200. A counterweight 203 may alsobe provided fast on the shaft 200 to minimize vibration of the sewingmachine.

Secured to the shaft 200 by a set screw 204 is a feed driving eccentric205 which in the assembled relation of parts is spaced from the bushing182 by a collar 206. Secured to the eccentric 205 by screws 207 is ahandwheel 208 formed with two annular belt pulley grooves 209 and 210.The belt pulley groove 209 accommodates a drive belt 211 from anysuitable source of power, such as for instance, as a drive pulley 212 onthe electric motor 213 supported on a bracket 214 secured by screws 215to the plate 180. The belt pulley groove 210 accommodates a drive belt216 which runs over a pair of idler pulleys 217 and 218 carried on theplate 180 and is directed about the pulley 123 on the loop taker 104.Preferably using the thread manipulating and stitching instrumentalitiesillustrated in the drawings, the handwheel pulley 210 is three times thediameter of the pulley 123 on the loop taker so that a speed ratio ofapproximately three revolutions of the loop taker will be maintained foreach reciprcation of the needle.

For driving the work feeding mechanism, the feed driving eccentric 205is embraced by two pitman straps 220 and 221 which, as illustrated inFIG. 3, extend substantially at right angles to each other. The pitmanstrap 220 extends substantially vertically downward and is pivoted to acylindrical boss 222 formed on a vertical link 223 which is constrainedto move in a slot 224 in the supporting plate 180. At the lowerextremity the link 223 is formed with a lengthwise slot 225 along whichan extension abutment 226 may be selectively clamped between nuts 227and 228 on a headed fastening screw 229. The extension abutment 226 maybe formed with an inturned tang 30 extending into the slot 225 toprevent the abutment from turning. The fastening screw 229 extendsthrough a vertical guide slot 231 formed in the plate 180.

FIG. 5 illustrates the position of parts when both the actuating module14 and the loop taker module are assembled on the frame 11. The feedlift lever 173 will pass through the guide slot 231 beneath the abutmentextension 226. A tension spring 232 arranged to act between the lever173 and an anchor pin 233 fixed in the plate 182 biases the lever 173into engagement with the. abutment extension 226.

Referring to FIGS. 3 and 5, the feed advance rock shaft 163 extendsthrough an aperture 239 in the plate 180 when the parts are assembled onthe frame. A rock arm 240 is secured to the rock shaft 163 by a setscrew 241. A link 242 pivoted to the rock arm 240 by a pivot pin 243 isalso connected by a pivot pin 244 to the pitman strap 221 which extendsgenerally horizontally from the feed eccentric 205. Journaled on thepivot pin 244 is a slide block 245 which is constrained to move alongthe diametrical slot 189 in the collar 188. Adjustment of the angularposition of the slot 189 by means of the finger grip 187 will determinethe direction in which the work will be fed and the length of the feedstep at each stitch.

In assembling the sewing machine of this invention, the support block 30of the frame 11 may be secured to a base 250 or to a table, carryingcase, or the like as is desired. The actuating module 14 is then securedin place by the screws 22 and 23. The loop taker module 13 is thensecured in place using the screws 101 and 102 taking care that the feedlift lever 173 is inserted through the slot 231 and the feed lift rockshaft is inserted into the bore in the rock arm 240 in the actuatingmodule support plate 189 when the spring 232 is attached to the feedlift lever 173. The set screw 241 is tightened to complete the feedadvance connection, and when the belt 216 is entrained on the pulleys123, 210, 217 and 218, and the loop taker and work feed mechanism willbe operatively installed on the frame.

The needle module 12 is then installed simply by placing the bore 42 ofthe block 41 on the cylindrical portion 18 of the frame arm 15 andsimultaneously inserting the shaft 200 in the axial bore 58 of the studshaft 54. The support plate 40 of the needle module 12 may then beturned and slid axially upon the cylindrical portion 18 of the frameuntil the needle 51 is accurately aligned with the needle aperture 168'of the throat plate on the loop taker module in place. The set screw 202is then tightened to connect the needle bar drive and the sewing machinewill be completely assembled.

Since the stud shaft 57 is accommodated in a spherical bearing seat 55in the support plate 40 of the needle bar module, and the bearing seat181 for the shaft 200 in the supporting plate 180 of the actuatingmodule is similarly spherical, considerable variation in the relativepositions of the support plates 40 and 180 on the frame 11 may beaccommodated without binding of the shaft 200. The construction of theneedle thread take up arm 65 as an integral part of the needle bar drivelink 63 makes possible this advantageous utilization of the selfaligning bearings 55, 181 because this take up construction obviates theneed for any anchor links between the take up arm 65 and the supportingframe as exist in conventional link type take ups. A shaft which drivesa conventional link take up having a pivot pin or anchor link connectionwith the machine frame must be manufactured in predetermined spacing andalignment with the pivot pin or anchor link connection, whichrequirement in the present invention would obviate the advantages of theself aligning bearings 55, 181.

Referring to FIGS. 2 and 10, it will be noted that the take. up arm 65projects toward the rear of the sewing machine substantiallyperpendicularly from the needle bar drive link 63 at a point oppositethe pivotal connection provided by the pin 52 with the needle bar.Moreover, the distance of the take up eyelet 66 from the pivot pin 52 isapproximately twice the distance between the pivot pins 52 and 62. Withthis construction, as illustrated in FIG. 10, the path of the eyelet 66on the take up arm is a flattened figure eight oriented substantiallyparallel to the axis of the needle bar 49. Optimum efficiency of threadmetering will thus be obtained relatively to the check spring 83 aboutwhich the thread approaches the eyelet 66 and the thread guide eyelet 85to which the thread extends from the eyelet 66, since both the checkspring 83 and the eyelet 85 may be arranged at substantially the samedistance from the axis of the needle bar reciprocation as is the path ofrotation of the take up eyelet 66.

As illustrated in FIG. 10, the path of motion of the take up eyelet 66substantially parallel to the axis of the needle bar makes possibleeffective and convenient shrouding of the operating mechanism on theneedle bar module 12 by a cover plate 250 which may follow thefunctional substantially rectangular outline of the support plate 40,without the requirement for flanges, lips, or extensions, in order toshroud the movement of the take up arm 65.

The graph illustrated in FIG. 11 indicates the cooperative relationshipbetween the manner in which the needle thread is metered by the take upeyelet 66 and the demands of the stitch forming instrumentalities uponthe needle thread during stitch formation. This graph plots as abscissathe needle bar crank angle, and as ordinate the total lengths of threadon the one hand as made available by the take up, and on the other handas demanded by the stitch forming instrumentalities including the rotaryhook 104 which is driven at approximately three revolutions for eachneedle reciprocation. The curve illustrated in dashed lines and labeledTAKE UP indicates the thread made available at each crank angle by thetake up while the curve illustrated in solid lines indicates thecorresponding thread demanded by the stitch forming instrumentalities.

As described hereinabove, the loop taker 104 is preferably of the typein which the motion imparted to the needle loop seizing beaks 129 neednot be timed precisely relatively to the needle reciprocation, it beingimmaterial to stitch formation which of the beaks 129 seized the needlethread. The thread demand curve in FIG. 11, therefore, from the points Aand B to the points C and D widens into an area or family of parallelcurves depending at each stitch upon the actual time at which loopseizure occurs. Similarly from the points C and D to the point E thedemand must be represented by a family of curves since the cast off ofthe thread from a stored position on the bobbin case may be influencedby the actual time at which loop seizure occurs.

Whereas in conventional lockstitch sewing machines in which the looptaker is driven in precise timed relation with the needle reciprocation,the take up need satisfy only one predetermined thread demand, in themachine of the preferred form of this invention, the take up mustsatisfy whichever one of the family of different thread demands mayoccur. As illustrated in FIG. 11 the thread supplied by the take up ofthis invention adequately incompasses the entire range of thread demandswhich are imposed by these stitch forming instrumentalities.

Having thus set forth the nature of this invention, what is claimedherein is:

1. A sewing machine for forming lockstitches comprising in combinationan endwise reciprocatory needle bar, a thread carrying needle secured tosaid needle bar, drive means for said needle bar including a rotarycrank means and a drive link pivotally connected to said crank means andto said needle bar, a rotary loop taker having a plurality of needleloop seizing beaks disposed to move in a path complemental to saidthread carrying needle, drive means for imparting rotation to said looptaker not in predictably timed relation with said needle reciprocationand at a nominal rate of substantially three revolutions during eachreciprocation of said needle bar, said rotary loop taker formingstitches with a needle thread seized from said needle when said needleis operated not in predictably timed relation with said rotary looptaker, and a needle thread take up arm extending laterally from saidneedle bar drive link and formed with a thread guiding eyelet providinga take up for thread carried by said needle.

2. A sewing machine as set forth in claim 1 characterized in that saiddrive means for said needle bar connected to said needle bar crank, andin which said drive means for said loop taker comprises a belt having auniform cross sectional configuration operatively connecting said shaftwith said loop taker.

3. A sewing machine as set forth in claim 1 in which an imaginary linepassing through said thread engaging eyelet and the pivoted connectionbetween said needle bar with said needle bar drive link extendssubstantially perpendicular to an imaginary line joining the axes of thepivoted connections of said needle bar drive link with said crank meansand with said needle bar, and in which said take up arm is substantiallytwice the length of said needle bar drive link.

4. A sewing machine as set forth in claim 3 in which a pair of threadguides are carried by said sewing machine, one for each limb of a loopof thread directed to said take up thread engaging eyelet, said threadguides being disposed in close proximity one to the other both at 9 10the same side of the path of motion of said take up thread FOREIGNPATENTS engaging eyelet and both substantially at the same dis- 722,6687/1942 Germany tance from the axis of needle bar reciprocation as is thepath of motion of said take up thread engaging eyelet. HAMPTON HUNTER,Primary Examiner References Cited 5 C1. UNITED STATES PATENTS 112--184,220, 241

1,062,696 5/1913 COX 112-181 1,129,588 2/1915 Onderdonk 112241 2,633,0923/1953 Robert et a1. 112220 10

